There are many different types of printers and print services in the market today. All of these printers are controlled with hardware and software that instructs the printer how to print content on a page. These instructions are generally referred to as printer language sets. Examples of printer language sets are Adobe PostScript and Printer Control Language. Any of these instruction sets exploit the characteristics of the printer being used and allows for the control of any brand of printer.
In order to print color onto a page, printers may use any color model in any color-space such as RGB or CMYK; current printers in the marketplace use a full range of colors based on a method called four color process printing. Four color process printing uses three primary ink colors cyan (C), magenta (M), and yellow (Y) plus Key (K) (“CMYK”). Key is generally black in four color process printing. Cyan, magenta, and yellow are the three main pigments used for color reproduction. When these three colors are combined in printing, the result should be a reasonable reproduction of the original, but in practice this is not the case. Due to limitations in the ink pigments, the darker colors are dirty and muddied. To resolve this, a technique called black replacement is used. One method of replacement (black replacement) is to replace highly saturated CMY values with the Key color. An example printer replaces color within a 25% range of theoretical black (fully saturated CMY) with K. This is done to increase the quality of the color, but is also done because black ink is typically less expensive then colored ink.
While black replacement is beneficial for everyday home/home office printing there are several applications in which the detail or intensity of black is important to the user, such as the digital pen industry. In the digital pen industry, the pen generally requires a location-encoding pattern printed on a surface to orient the pen or any other perceiving device having the ability to recognize a qualitative difference between a material used for a location encoding pattern and a material used for content. A surface is generally defined as any printable medium that can accept a print coating, injection, or fusion. By way of example the pattern may be printed with pure black ink, infrared absorbing ink, ultra violet ink or any material that can be distinguished from content material that is detectable by an infrared or other type of sensor in the pen. Content, which is defined as text, a map, images or any printable subject matter, may be placed over the pattern to allow a user with the pen to manipulate the document. If the content is placed over the location-encoding pattern and the content uses black ink (in this case both the content and the pattern using the same material) then the content may interfere with the pattern not allowing the pen to effectively locate itself on the page.